1. Field of the Invention
The present invention relates to an LC component, and more particularly, to a surface mount type LC component for use as a noise filter.
2. Description of the Related Art
An example of a conventional LC component is shown in FIG. 14. In an LC component 1, terminal electrodes 2 and 3 are provided on both ends of a columnar wound core member having a spiral coil provided around the peripheral surface thereof. A dielectric layer 7 is provided on the central surface of the wound core member so as to cover the spiral coil. Further, on the dielectric layer 7, a ring capacitor electrode 8 is provided and wound once around the wound core member in the outer peripheral direction. FIG. 15 is an equivalent electric circuit diagram of the LC component 1.
The ring capacitor electrode 8 functions as a one turn coil, a so-called short ring, because it is wound once around the peripheral surface of the wound core member. For this reason, a magnetic flux caused by an electric current flowing through the spiral coil is interlinked with the ring capacitor electrode 8 so that an induced current flows in the ring capacitor electrode 8. The induced current circulates in the capacitor electrode 8 consuming energy. Therefore, the conventional LC component 1 has the problem that the Q value and the inductance of the spiral coil are low.
To overcome the problems described above, preferred embodiments of the present invention provide an LC component in which a capacitor electrode does not function as a short ring, and the Q value and the inductance of a coil are high.
According to a first preferred embodiment of the present invention, an LC component includes a wound core member, a coil conductor spirally wound around the outer peripheral surface of the wound core member, a dielectric layer arranged to cover the coil conductor, a capacitor electrode provided on the dielectric layer, and a cut groove arranged to divide the capacitor electrode.
According to a second preferred embodiment of the present invention, an LC component includes a wound core member having a substantially rectangular cross-section, a coil conductor spirally wound around the outer peripheral surface of the wound core member, a dielectric layer arranged to cover the coil conductor, a capacitor electrode provided on the dielectric layer so as to wind approximately once around the wound core member in the outer peripheral direction of the wound core member, a first cut groove crossing the capacitor electrode from one side of a first surface of the capacitor electrode to the other side of a second surface adjacent to the first surface, and a second cut groove crossing the capacitor electrode from one side of a third surface of the capacitor electrode to the other side of a fourth surface adjacent to the third surface.
According to a third preferred embodiment of the present invention, an LC component includes a wound core member having a substantially circular cross-section, a coil conductor spirally wound around the outer peripheral surface of the wound core member, a dielectric layer arranged to cover the coil conductor, a capacitor electrode provided on the dielectric layer so as to wind approximately once around the wound core member in the outer peripheral direction of the wound core member, and having four areas in the outer peripheral direction of the wound core member, a first cut groove crossing the capacitor electrode from one side of the first area of the capacitor electrode to the other side of the second area adjacent to the first area, and a second cut groove crossing the capacitor electrode from one side of the third area of the capacitor electrode to the other side of the fourth area adjacent to the third area.
The coil conductor is preferably a spiral coil formed by laser working, or other suitable methods.
The capacitor electrode preferably has a band shape but may have other suitable shapes.
The coil conductor covered with the dielectric layer is protected by the dielectric layer. The dielectric layer constituting the capacitor also functions as a protection layer for the coil conductor.
The capacitor electrode does not function as a short ring because it is divided by the cut groove. That is, when a magnetic flux caused by a current flowing through the coil conductor is interlinked with the capacitor electrode, no circulating current flows in the capacitor electrode. As a result of this unique arrangement, the Q value and the inductance of a coil are high.
Other features, characteristics, elements and advantages of the present invention will become apparent from the following description of preferred embodiments thereof with reference to the attached drawings.